1. Field of the Invention
The present invention relates to a light guide plate and a light-emitting apparatus. More particularly, the present invention relates to a laminated light guide plate, which uses a reflective material and micro-structures to limit the light-emitting angles in a small range, and generates an air gap by means of partial lamination, so as to reduce the light absorption of the reflective material, such that the light-emitting apparatus using the light guide plate has a high light-emitting efficiency.
2. Description of Related Art
With the maturity of photoelectric technology and semiconductor manufacturing technology, flat panel displays are developed rapidly. Among them, liquid crystal displays (LCD), having advantages of low operating voltage, no radiation, light weight, and small volume, gradually replace the conventional cathode ray tube displays and become mainstream display products in recent years.
Generally speaking, LCD panels are non-self-light-emitting display panels and need a backlight module to provide a backlight source. Usually, an edge-lit type backlight module includes a light guide plate and at least one light source. The light guide plate functions to convert a point or linear light source into a planar light source. FIG. 1 is a schematic view of a conventional edge-lit type backlight module. Referring to FIG. 1, a conventional edge-lit type backlight module 100 includes a light source 110, a light guide plate 120, and a reflector 130, as well as four optical films including two diffusers 140 and two prism sheets 150. The prism sheets 150 are also referred to as brightness enhancement films (BEF) for deflecting light rays to a normal viewing direction, thus having the effects of gathering light and enhancing brightness. The diffusers 140 have the function of light diffusion and making the brightness distribution of light become uniform. Therefore, in order to improve the using efficiency of the light source and achieve the effect of power saving, the conventional backlight module 100 mostly adopts a plurality of optical films. The cost of the films takes up to 30%-40% of the total cost of the backlight module 100, thus leading to a high cost of the backlight module 100. Furthermore, the films also occupy a certain space, so that the thickness and volume of the backlight module 100 are difficult to be reduced.
Furthermore, a reflector 130 is generally disposed below the light guide plate 120. Patents U.S. Pat. No. 5,961,198 and TW 486,101 disclose a technique of plating a reflective layer on a light guide plate without disposing a reflector in the backlight module. When the light is delivered in the light guide plate, the light is frequently reflected by the interface and keeps conducting in the light guide plate. If the reflection is totally reflection with the difference of reflection index, the interface absorption may be regarded as zero. However, the reflectivity of a common metal is 90-98%, and the interface absorption after multiple times of reflections cannot be neglected, and may even be 30% or above. For example, when a reflective layer having a reflectivity of 95% is used together with a light guide plate of 0.3 mm to 1.0 mm thick, under a deliver length of 80 mm, the light absorption of the metal is approximately 20% to 50%. Therefore, the practicality of this technique is reduced because of the problem of high absorption of the reflective material. If the light absorption can be greatly reduced when only depositing a reflective material on the micro-structures, the practicality of the technique may be improved.